Abstract
It is well established that attentional cueing can facilitate processing of low-level visual attributes. However, it is unclear whether expectation at the category level can also result in facilitated processing. Here, we addressed this question by examining the effects of category-level cues on performance on a visual discrimination task. Stimuli were generated by morphing two “parent” images in varying degrees. One set consisted of morphs between two faces and another consisted of morphs between two places. On each trial, a valid (60% of trials) or invalid (20% of trials) category-level cue (“FACE”, “PLACE”), or a neutral (20% of trials) cue (“XXXXX”) was presented, followed by presentation of a morphed stimulus. Participants were required to decide which of the parent images was closer to the morph. Discriminability was higher after valid cues than after invalid cues, indicating that perception was enhanced when subjects were expecting the correct category. This effect could not be attributed to “unexpectedness” of targets in the invalid condition, because performance on valid trials was also improved relative to neutral trials. Additionally, analyses of RT data revealed that responses were faster after valid cues than after invalid cues. These results are consistent with the possibility that category-level expectation can enhance discrimination of complex visual stimuli.